Artificial spinal disc and artificial disc insertion method using the same

ABSTRACT

An artificial spinal disc including an upper disc formed in a plate shape with top coupled to an upper vertebra, a protruding joint portion protruding from a lower surface of the upper disc, and a lower disc formed in a plate shape with bottom coupled to a lower vertebra wherein the protruding joint portion is seated on an upper surface of the lower disc. According to the foregoing description, the artificial disc is implanted through the lateral or anterolateral approach to the spine, rather than the anterior approach, and such lateral implantation is straightforward.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 17/424,883 filed on Jul. 21, 2021, which is anational-stage entry of international application No. PCT/IB2021/050930filed on Feb. 5, 2021, and claims priority to Korean patent applicationNo. 10-2020-0045107 filed on Apr. 14, 2020, and the entire contents ofthe mentioned applications are hereby incorporated by reference.

TECHNICAL FIELD

The present disclosure relates to an artificial spinal disc and anartificial disc insertion method using the same, and more particularly,to an artificial spinal disc which is used to replace a damaged disc inthe spine for the treatment of a spinal disc related disease and anartificial disc insertion method for inserting an artificial disc intothe spine.

BACKGROUND ART

In general, discs serve as cushions between vertebrae to absorb loadsand impacts of the body applied to the spinal column. Discs distributeimpacts like springs, hold the vertebrae not to move out of place,separate two vertebrae to prevent nerve compression in the neuroforaminain motion, and help each vertebra to move smoothly.

Meanwhile, since discs frequently absorb and transmit vertically appliedloads and impacts, a variety of diseases associated with disc trauma canoccur, such as spinal stenosis, osteophyte formation, disc herniation,and nerve root compression. One treatment method for diseases associatedwith discs involves removal of a damaged intervertebral disc, andimplanting an artificial disc in the space between two adjacentvertebrae to restore the function of the spine.

The artificial disc generally should have a proper thickness andanatomic restoration to restore the original height of theintervertebral disc.

Meanwhile, as an example of a conventional artificial disc, KoreanPatent No. 10-1964862 discloses an artificial disc for cervical spineincluding an upper plate, a lower plate and an elastic member, a firstgroove formed in the shape of a dome on the bottom of the upper plate toreceive the top of the elastic member, a circular second groove formedon the upper surface of the lower plate to receive the bottom of theelastic member, a concave portion formed in the shape of a dome recesseddownward from the second groove of the lower plate to prevent contactwith the bottom of the elastic member, a plurality of upper slots formedon the upper surface of the upper plate in the horizontal direction toprevent anterior movement of the artificial disc, and a plurality oflower slots formed on the bottom of the lower plate in the horizontaldirection to prevent anterior movement of the artificial disc.

However, the conventional artificial discs require an intricatemanufacturing process due to their complex shapes, and often fail toeffectively ensure spinal mobility after surgery.

Additionally, the conventional artificial discs are implanted by theanterior approach to the spine through the abdomen, and since theanterior approach involves abdominal insertion and implantation, theartificial disc passes through the main arteries and the main veins.Thus, there is an increased risk of damage to the major blood vesselsduring surgery. Furthermore, the implantable artificial disc may migrateforward, causing a serious danger to the vital structures near thespine.

DISCLOSURE Technical Problem

The present disclosure is directed to providing an artificial spinaldisc which has a simple shape, is easy to manufacture, improves spinalmobility for a patient with a damaged disc and ensures stability aftersurgery, and an artificial disc insertion method using the same.

The present disclosure is further directed to providing an artificialspinal disc which is implanted by the lateral or anterolateral approachto the spine, not the anterior approach, and has an optimal shape foreffective lateral implantation to reduce the risk of damage to the majorvessels or other vital organs, which may be caused by surgery using theanterior approach, and an artificial disc insertion method using thesame.

Technical Solution

The present disclosure provides an artificial spinal disc insertedbetween an upper vertebra and a lower vertebra, the artificial spinaldisc including an upper disc formed in a plate shape, with top coupledto the upper vertebra, a protruding joint portion including a main jointportion protruding from a lower surface of the upper disc, and one ormultiple auxiliary joint portions spaced apart from a side of the mainjoint portion and protruding from the lower surface of the upper disc,and a lower disc formed in a plate shape, with bottom coupled to thelower vertebra, the lower disc having, on an upper surface, a main jointgroove in which the main joint portion is seated and an auxiliary jointgroove in which the auxiliary joint portion is seated to allow theprotruding joint portion to make multidirectional movements.

Here, the auxiliary joint portion may include a first auxiliary jointportion disposed at a distance on one horizontal side of the main jointportion, and a second auxiliary joint portion disposed at a distance onthe other horizontal side of the main joint portion.

Preferably, the first auxiliary joint portion and the second auxiliaryjoint portion are symmetrically disposed with respect to the main jointportion on a plane.

Each of the first auxiliary joint portion and the second auxiliary jointportion may be formed in a hemispherical shape.

Alternatively, each of the first auxiliary joint portion and the secondauxiliary joint portion may be formed in a semi-ellipsoidal shape. Inthis case, each of the first auxiliary joint portion and the secondauxiliary joint portion may be formed such that a long axis connectingtwo points on a plane is disposed along a front-rear direction of aspine.

The main joint portion may be formed in a hemispherical shape.

Alternatively, the main joint portion may be formed in asemi-ellipsoidal shape. In this case, the main joint portion may beformed such that a long axis connecting two points on a plane isdisposed along a left-right direction of a spine.

The main joint portion may protrude higher than a protrusion height ofthe auxiliary joint portion.

Further, the protruding joint portion may be integrally formed with theupper disc.

Preferably, the upper disc and the lower disc are spaced apart from eachother at a distance between the lower surface of the upper disc and theupper surface of the lower disc in a range of 3 mm to 6 mm when theprotruding joint portion is seated.

Preferably, the first auxiliary joint portion and the second auxiliaryjoint portion are formed with a smaller planar area than a planar areaof the main joint portion.

The auxiliary joint portion may be formed such that a center of each ofthe first auxiliary joint portion and the second auxiliary joint portionis disposed at an anterior portion of a spine with respect to a centerof the main joint portion on a plane.

The first auxiliary joint portion and the second auxiliary joint portionmay be configured to have a same shape and planar area.

The upper disc and the lower disc may include a first side formed alongone anterior side of the main joint portion and one anterior side of thefirst auxiliary joint portion, a second side having one side connectedto one side of the first side and formed along the other anterior sideof the main joint portion and one anterior side of the second auxiliaryjoint portion to form a set angle with the first side, and a third sidehaving one side connected to the other side of the first side and theother side connected to the other side of the second side and formedalong one posterior side of the first auxiliary joint portion and oneposterior side of the second auxiliary joint portion.

The upper disc and the lower disc may have a plane shape of anapproximate triangular shape formed by the first side, the second sideand the third side.

Meanwhile, the upper disc and the lower disc may be formed in the shapeof an isosceles triangle such that two insertion sides of the firstauxiliary joint portion or the second auxiliary joint portion are narrowand the third side is long in the horizontal direction, when insertedthrough the lateral or anterolateral approach to the spine. In thisinstance, an angle between the first side and the second side withrespect to the third side may be 18° to 22°, or an internal angle ofintersection between a first imaginary line connecting the center ofeach of the first auxiliary joint portion and the second auxiliary jointportion and a second imaginary line connecting the center of each of themain joint portion, the first auxiliary joint portion and the secondauxiliary joint portion may be 18° to 22°.

Each of the upper disc and the lower disc may be arranged with the thirdside facing an anterior side of a spine.

Each of the upper disc and the lower disc may be configured to have oneor multiple concave portions on the third side.

The upper disc and the lower disc may include a first curved side formedalong an anterior side of each of the first auxiliary joint portion, themain joint portion and the second auxiliary joint portion, and curvedconcavely on a plane, and a second curved side connected to the firstcurved side, formed along a posterior side of each of the firstauxiliary joint portion, the main joint portion and the second auxiliaryjoint portion and curved convexly on the plane.

According to another aspect of the present disclosure, the presentdisclosure provides an artificial disc insertion method includinginserting an artificial disc into an implantation space between an uppervertebra and a lower vertebra of a human body, the artificial discincluding an upper disc formed in a plate shape, with top coupled to theupper vertebra, a protruding joint portion including a main jointportion protruding from a lower surface of the upper disc and one ormultiple auxiliary joint portions spaced apart from a side of the mainjoint portion and protruding the lower surface of the upper disc, and alower disc formed in a plate shape, with bottom coupled to the lowervertebra, the lower disc having, on an upper surface, a main jointgroove in which the main joint portion is seated and an auxiliary jointgroove in which the auxiliary joint portion is seated to allow theprotruding joint portion to make multidirectional movements, wherein theartificial disc is inserted through a lateral or anterolateral approachto a spine and the auxiliary joint portion is first inserted into theimplantation space, pushing the artificial disc into the implantationspace such that the main joint portion is disposed at a center of theupper vertebra and the lower vertebra on a plane, and adjusting alocation of the artificial disc.

Advantageous Effects

The artificial spinal disc according to the present disclosure and theartificial disc insertion method using the same may provide thefollowing effects.

First, the artificial spinal disc according to the present disclosure iseasy to manufacture due to its simple shape, and it is possible toimprove the spinal mobility and ensure stability after surgery.

Second, it is possible to perform safer surgery without any risk ofdamage to blood vessels or other organs that may occur due to surgeryusing the anterior approach. This advantage is achieved by implantingthe artificial disc with either the lateral or anterolateral approach tothe spine, rather than the anterior approach, to avoid risking the vitalstructures in the human body, and by optimizing the shapes of the upperdisc and the lower disc to make lateral or anterolateral implantationeasier.

Third, the artificial spinal disc according to the present disclosureallows for broader and more free movements, as the location of thecenter of rotation and the slope of the spine through the main jointportion and the auxiliary joint portion are configured to closely mimicnatural movements of the spine to the greatest extent, therebypreventing stress and fatigue with the surrounding tissues and improvinga patient's joint mobility.

Fourth, the protruding joint portion includes the main joint portion aswell as two auxiliary joint portions to increase the contact surface ofthe joint within the artificial disc, thereby greatly increasing thestability of spinal mobilization after surgery. Additionally, since theincreased contact surface through the main joint portion and the twoauxiliary joint portions ensures stability, it is possible to resolveissues concerning the reduced area of the center of rotation that may beinvolved in the lateral or anterolateral approach.

DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view showing an artificial spinal disc according to anembodiment of the present disclosure inserted into the spine.

FIG. 2 is a plan view showing an artificial spinal disc insertion methodaccording to an embodiment of the present disclosure.

FIG. 3 is an exploded perspective view of an artificial spinal discaccording to an embodiment of the present disclosure.

FIG. 4 is plan and front views showing an upper disc of an artificialspinal disc according to an embodiment of the present disclosure.

FIG. 5 is plan and front views showing a lower disc of an artificialspinal disc according to an embodiment of the present disclosure.

FIG. 6 is a front view of an artificial spinal disc according to anembodiment of the present disclosure.

FIG. 7 is a side view of an artificial spinal disc according to anembodiment of the present disclosure.

FIG. 8 is a plan view showing another embodiment of an auxiliary jointportion of an artificial spinal disc according to an embodiment of thepresent disclosure.

FIG. 9 is a plan view showing another embodiment of concave portionsformed on the sides of an upper disc and a lower disc of an artificialspinal disc according to an embodiment of the present disclosure.

FIG. 10 is a plan view showing another embodiment of an upper disc and alower disc of an artificial spinal disc according to an embodiment ofthe present disclosure.

FIG. 11 is a plan view showing another embodiment of a main jointportion of an artificial spinal disc according to an embodiment of thepresent disclosure.

FIG. 12 is a plan view showing another embodiment of a main jointportion and an auxiliary joint portion having different shapes in anartificial spinal disc according to an embodiment of the presentdisclosure.

FIG. 13 is a plan view showing another embodiment of an upper disc and alower disc having different side shapes in an artificial spinal discaccording to an embodiment of the present disclosure.

FIG. 14 is a perspective view showing another embodiment of an auxiliaryjoint portion of an upper disc and an auxiliary joint groove of a lowerdisc in an artificial spinal disc according to an embodiment of thepresent disclosure.

BEST MODE

Hereinafter, the preferred embodiments of the present disclosure will bedescribed in detail with reference to the accompanying drawings.

First, the present disclosure is inserted and implanted into animplantation space between an upper vertebra and a lower vertebra inplace of a damaged disc after the damaged disc is removed, and FIG. 1 isa plan view showing an artificial spinal disc 500 according to anembodiment of the present disclosure (hereinafter referred to as an‘artificial disc’) implanted into the spine. In the drawing, thereference number 1 indicates the spinal cord, and the reference number10 indicates the transverse process of the vertebra.

Meanwhile, as shown in FIG. 2 , an artificial disc insertion methodaccording to an embodiment of the present disclosure inserts theartificial disc 500 into the implantation space between the uppervertebra and the lower vertebra through the lateral or anterolateralapproach to the spine, and as opposed to the conventional anteriorapproach of inserting the artificial disc 500 from the anterior of thespine, this approach avoids the major organs, blood vessels and so on,thereby minimizing the risk of injury associated with artificial discreplacement surgery.

Additionally, since the artificial disc 500 of the present disclosure isinserted through the lateral or anterolateral approach to the human bodyas opposed to the conventional anterior approach, when considering this,the artificial disc 500 may be formed in an anatomically optimal shapeto ease the insertion and implantation through the lateral oranterolateral approach to the spine and minimize tissue damage.

Prior to description of the artificial disc 500, the method forinserting the artificial spinal disc will be described with reference toFIG. 2 .

First, the artificial disc 500 is coupled to an insertion instrument(not shown) and inserted into the implantation space between the uppervertebra and the lower vertebra in the human body through the insertioninstrument to a set location on the lateral or anterolateral position ofthe spine. Describing the artificial disc insertion method in detail,first, the narrow side of the artificial disc 500 in which a firstauxiliary joint portion 221 or a second auxiliary joint portion 222 isdisposed as described below is inserted into the implantation space. Inthis instance, since the artificial disc 500 has two narrow sides and awide center, the side of the artificial disc 500 formed in a narrowshape for an easy entry into the tissue in the human body is firstinserted, in which the first auxiliary joint portion 221 or the secondauxiliary joint portion 222 is disposed.

When the first auxiliary joint portion 221 or the second auxiliary jointportion 222 is first inserted, the artificial disc 500 is pushed intothe implantation space to place a main joint portion 210 and the secondauxiliary joint portion 222 or the first auxiliary joint portion 221 inthe implantation space. In this instance, the main joint portion 210 maybe disposed at the center of the upper vertebra and the lower vertebraon the plane in the implantation space, and this is a location takingthe movement of the spine into account, and the location may be changeddepending on the shape of the corresponding spine.

Meanwhile, since the artificial disc 500 is inserted by the lateral oranterolateral approach to the spine, when the artificial disc 500 isinserted into in the implantation space, the first auxiliary jointportion 221 and the second auxiliary joint portion 222 are not disposedon the same horizontal line and they are slanted at a set angle. Thus,when the insertion of the artificial disc 500 is completed, it isnecessary to adjust the location of the artificial disc 500.

Accordingly, the method ends with adjusting the location of theartificial disc 500 by axially rotating the artificial disc 500 so thatthe first auxiliary joint portion 221 and the second auxiliary jointportion 222 are disposed on the same horizontal line facing the anteriorside of the spine, with the main joint portion 210 disposed at theinstallation location, i.e., at the center of the upper vertebra and thelower vertebra on the plane, as shown.

According to the foregoing description, due to the insertion through thelateral or anterolateral approach to the spine, the artificial discinsertion method of the present disclosure avoids the major organs, themain arteries, the main veins and so on, thereby preventing damage tothe human body that may occur during the surgery, and reducingunnecessary dissection, which facilitates post-operative recovery.Additionally, due to the insertion through the lateral or anterolateralapproach to the spine, the artificial disc insertion method of thepresent disclosure can preserve the anterior longitudinal ligament (ALL)in the insertion process, thereby avoiding potentially devastatingcomplications that may occur with anterior extrusion of the artificialdisc.

Meanwhile, since it is inserted through the lateral approach to thespine, not the anterior approach, the artificial disc 500 is formed witha small width and a large horizontal length for easy lateral insertion,and configured to be inserted using the narrow side as an insertion end.

In other words, the artificial disc 500 is formed in an optimal shapefor easy lateral insertion into the spine, and hereinafter the detailsincluding the shape of the artificial disc 500 will be described.

Referring to FIG. 3 , the artificial spinal disc 500 according to anembodiment of the present disclosure is inserted into the implantationspace between the upper vertebra and the lower vertebra adjacent to eachother, and may include an upper disc 100, a protruding joint portion 200and a lower disc 300.

First, the upper disc 100 is formed in the shape of a plate having a setthickness, and is coupled and fixed to the bottom of the upper vertebrain the implantation space from which the disc has been removed. Althoughthe drawing shows the upper disc 100 formed with an equal width(height), this is an example and the upper disc 100 may be formed with atapered thickness or varying thickness of each location depending on theshape of the implantation space or the shape of the upper vertebra.

Although not shown, the upper disc 100 may be fixed with the uppervertebra through a fixing means. Here, for fixing with the uppervertebra, the fixing means may include a wedge type fixing protrusion(spike) protruding from the upper surface of the upper disc 100, aporous surface to facilitate the bone growth or a fixing pin, and avariety of other configurations for fixing with the upper vertebra maybe applied. The fixing means may be integrally formed with the upperdisc 100 into a product in the manufacture of the upper disc 100.

The plane of the upper disc 100 may have an approximate triangular shapeas shown, to facilitate the lateral insertion into the spine. However,this is an example, and the upper disc 100 may be formed in variousshapes including a streamlined or kidney bean shape, and variousembodiments of the upper disc 100 will be described in FIGS. 9, 10 and12 below.

Meanwhile, when the upper disc 100 is formed in the shape of a trianglehaving a first side 110, a second side 120 and a third side 130 on theplane, a concave portion 131 may be formed on the third side 130 asshown. To contribute to the material reduction and facilitate theinsertion, the concave portion 131 may be formed in various shapes.

Referring to FIG. 4 , the protruding joint portion 200 plays a role inallowing the upper disc 100 and the lower disc 300 to makemultidirectional free movements, and through this, closely mimickingnatural movements of the spine.

The protruding joint portion 200 protrudes downward from the lowersurface of the upper disc 100 and comes into contact with the uppersurface of the lower disc 300.

The protruding joint portion 200 may be integrally formed with the upperdisc 100 using the same material.

As shown in FIG. 4 , the protruding joint portion 200 may include themain joint portion 210 and one or multiple auxiliary joint portions 220.

The main joint portion 210 may be disposed at a location at which jointmovements of the spine are made or at the center of the vertebrae on theplane after the implantation of the artificial disc 500.

The main joint portion 210 may be formed in a hemispherical orsemi-ellipsoidal shape according to the settings of the range ofrotation and the center of mass.

Meanwhile, when the shape of the main joint portion (210 a in FIGS. 11,12 and 13 ) is a semi-ellipsoidal shape, the main joint portion 210 a ispreferably formed such that the long axis connecting two points on theplane is disposed along the left-right direction of the spine. Ingeneral, the spine has a larger range of forward-backward movement(extension, flexion) than the range of leftward-rightward movement(lateral bending), and considering this, the long axis is disposed alongthe left-right direction of the spine to further increase the range offorward-backward movement.

The main joint portion 210,210 a preferably protrudes to a larger heightthan the protrusion height of the auxiliary joint portion 220 (see FIG.6 ). The main joint portion 210,210 a responsible for main jointmovements has a large protrusion height for effective multidirectionalmovements.

The auxiliary joint portion 220 plays a role in maintaining the coronaland sagittal balance of the artificial disc 500, and complements andsupports the main joint portion 210,210 a that inevitably has a smallersize than the joint of the conventional artificial disc due to theinsertion through the lateral or anterolateral approach.

The auxiliary joint portion 220 is spaced apart from the side of themain joint portion 210, and protrudes from the lower surface of theupper disc 100. In the same way as the above-described main jointportion 210, the auxiliary joint portion 220 may be integrally formedwith the upper disc 100 using the same material.

Referring to FIG. 4 , a pair of auxiliary joint portions 220 may be eachdisposed on two sides of the main joint portion 210, spaced apart fromeach other, and may include the first auxiliary joint portion 221 andthe second auxiliary joint portion 222.

The first auxiliary joint portion 221 is disposed at a distance on onehorizontal side of the main joint portion 210. Additionally, the secondauxiliary joint portion 222 is disposed at a distance on the otherhorizontal side of the main joint portion 210.

Here, the first auxiliary joint portion 221 and the second auxiliaryjoint portion 222 may be configured with the same shape and planar area.

Additionally, each of the first auxiliary joint portion 221 and thesecond auxiliary joint portion 222 may be disposed symmetrically in thehorizontal direction with respect to the main joint portion 210 on theplane. In detail, each of the first auxiliary joint portion 221 and thesecond auxiliary joint portion 222 is configured such that its center isdisposed at the anterior portion of the spine with respect to the centerof the main joint portion 210 on the plane.

Additionally, the first auxiliary joint portion 221 and the secondauxiliary joint portion 222 may be formed with a smaller planar areathan the planar area of the main joint portion 210.

Here, the main joint portion 210, the first auxiliary joint portion 221and the second auxiliary joint portion 222 are preferably arranged inthe shape of an isosceles triangle having a long base by connecting thecenter of each of the main joint portion 210, the first auxiliary jointportion 221 and the second auxiliary joint portion 222 on the plane. Inthis instance, each of the main joint portion 210, the first auxiliaryjoint portion 221 and the second auxiliary joint portion 222 is disposedadjacent to each vertex location of the triangular shape on the plane,and in this state, the base corresponds to a line connecting the centerof each of the first auxiliary joint portion 221 and the secondauxiliary joint portion 222.

Meanwhile, referring to FIG. 4 , the upper disc 100 has the plane shapewhich is narrow on two sides and long in the horizontal direction on thewhole, to ease the lateral insertion into the spine, and this shapefacilitates the lateral insertion into the spine. In other words, theupper disc 100 may be formed in the shape of an isosceles trianglehaving the long third side 130 in the horizontal direction and twoinsertion sides of the first auxiliary joint portion 221 or the secondauxiliary joint portion 222 which are narrow when inserted in thelateral direction of the spine.

In detail, when it is assumed that the main joint portion 210 and thepair of auxiliary joint portions 220 are arranged in a triangular shape,an internal angle between two sides (the first side 110 and the secondside 120) with respect to the base (the third side 130) of the triangleis preferably 18° to 22°. Alternatively, an internal angle ofintersection between a first imaginary line connecting the center ofeach of the first auxiliary joint portion 221 and the second auxiliaryjoint portion 222 and a second imaginary line connecting the center ofeach of the main joint portion 210, the first auxiliary joint portion221 and the second auxiliary joint portion 222 is preferably 18° to 22°.

When the angle is less than 18°, the shape of the upper disc 100increases in the horizontal direction, and a space for formation of themain joint portion 210 reduces, resulting in reduced range of motion ofthe artificial disc 500. In contrast, when the angle is higher than 22°,the central width of the upper disc 100 increases and the lateralinsertion into the spine may not be easy.

The auxiliary joint portion 220 may be formed in a hemispherical orsemi-ellipsoidal shape. In this instance, when the auxiliary jointportion 220 is a semi-ellipsoidal shape, the auxiliary joint portion 220is preferably formed such that the long axis connecting two points onthe plane is disposed along the front-rear direction of the spine (seeFIG. 8 ).

Further, the main joint portion 210 may be spaced apart in the otherdirection with respect to one directional same tangent line of the firstauxiliary joint portion 221 and the second auxiliary joint portion 222on the plane, such that the upper side of the main joint portion 210 maybe disposed at the lower position than the upper side of the firstauxiliary joint portion 221 and the second auxiliary joint portion 222on the plane.

Referring to FIG. 5 , the lower disc 300 is disposed at a distance belowthe upper disc 100, formed in the shape of a plate having a setthickness, and coupled and fixed onto the lower vertebra of theimplantation space.

The lower disc 300 may be formed with the same width (height) and planeshape to match the upper disc 100, and may be fixed with the lowervertebra through the above-described fixing means. In the drawing, thelower disc 300 may be formed in an approximate triangular shape having afirst side 310, a second side 320 and a third side 330 to match theplane shape of the upper disc 100, and in the same way as the upper disc100, a concave portion 331 may be formed on the third side 330 as shown.

The lower disc 300 may have, on the upper surface, a joint groove inwhich the protruding joint portion 200 is seated to allowmultidirectional movements. The joint groove may be configured toprovide translational and rotational movements of the spine such asflexion, extension, side bending, and axial rotation (twisting), whilemaintaining slidable contact with the side of the protruding jointportion 200.

The joint groove may include a main joint groove 311 in which the mainjoint portion 210 is seated, and an auxiliary joint groove 312 in whichthe auxiliary joint portion 220 is seated.

Here, the main joint groove 311 may be formed in the same hemisphericalor semi-ellipsoidal shape to match the shape of the main joint portion210, and the auxiliary joint groove 312 may be formed in the samehemispherical or semi-ellipsoidal shape to match the shape of theauxiliary joint portion 220, to bring that the main joint portion 210and the auxiliary joint portion 220 into contact with the main jointgroove 311 and the auxiliary joint groove 312.

Meanwhile, an auxiliary joint groove 312 a may be formed in a differentshape from the corresponding auxiliary joint portion 220, not in thesame shape (see FIG. 14 ). The auxiliary joint portion 220 may be formedin a hemispherical shape and the corresponding auxiliary joint groove312 a may be formed in a semi-ellipsoidal shape, and its detaileddescription will be provided in FIG. 14 below.

The upper disc 100, the lower disc 300 and the protruding joint portion200 may be formed from metals such as titanium or carbon alloys orceramics which are harmless to the human body and can withstand impactsand loads applied to the spine for a long time, but a variety ofmaterials for achieving the above-described object may be applied.

Referring to FIGS. 6 and 7 , when the protruding joint portion 200 isseated, the upper disc 100 and the lower disc 300 are spaced a setdistance D apart from each other to allow the joint portion to move. Thedistance is a factor that affects the range of motion of the artificialdisc 500, and with the increasing distance, the thickness of the upperdisc 100 and the lower disc 300 reduces and the stability reduces, andwith the decreasing distance, the range of motion reduces. Accordingly,the artificial disc 500 preferably has the vertical distance between thelower surface of the upper disc 100 and the upper surface of the lowerdisc 300 in the range of 3 mm to 6 mm. As described above, when thedistance is less than 3 mm, the side of the upper disc 100 and the sideof the lower disc 300 interfere with each other during motion, whichaffects the motion of the artificial disc 500, resulting in reducedrange of motion. When the distance is more than 6 mm, since the totalheight from the upper surface of the upper disc 100 to the lower surfaceof the lower disc 300 is limited to a normal adult's disc insertionspace (height), with the increasing distance between the upper disc 100and the lower disc 300, the height (thickness) of the upper disc 100 andthe lower disc 300 reduces, causing a problem with durability and stablesupport.

Hereinafter, various embodiments of the upper disc 100, the lower disc300 and the protruding joint portion 200 will be described. Prior todescription, since the upper disc 100, the lower disc 300 and theprotruding joint portion 200 have been hereinabove described in detail,the detailed description is omitted herein, and the shape and locationof each element will be described in detail.

In a first embodiment, referring to FIG. 8 , the plane shape of theupper disc 100 (the lower disc) has an approximate isosceles triangleshape.

In detail, the upper disc 100 and the lower disc 300 may have the planeshape of a triangular shape including the first side 110, the secondside 120 and the third side 130.

The first side 110 is connected to one anterior side of the main jointportion 210 and one anterior side of the first auxiliary joint portion221 with respect to the main joint portion 210.

The second side 120 has one side connected to one side of the first side110 to form a set angle with the first side 110, and is connected to theother anterior side of the main joint portion 210 and one anterior sideof the second auxiliary joint portion 222. In this instance, the firstside 110 and the second side 120 correspond to two sides of the triangleexcept the base.

The third side 130 has one side connected to the other end of the firstside 110 and the other side connected to the other side of the secondside 120, is connected to one posterior side of the first auxiliaryjoint portion 221 and one posterior side of the second auxiliary jointportion 222, and corresponds to the base of the triangle.

As such, the upper disc 100 and the lower disc 300 may be formed in anapproximate triangular shape on the plane by the first side 110, thesecond side 120 and the third side 130.

Meanwhile, first, each of the upper disc 100 and the lower disc 300 ispreferably positioned such that the third side 130 faces the anteriorside of the spine, considering the insertion direction (see FIG. 1 ).

In FIG. 8 , the main joint portion 210 may be formed in a hemisphericalshape, and the first auxiliary joint portion 221 a and the secondauxiliary joint portion 222 a may be formed in a semi-ellipsoidal shape.In this instance, the auxiliary joint portion 220 is positioned in theup-down direction such that the long axis of the semi-ellipsoid facesthe front-rear direction.

Additionally, the main joint portion 210 may be configured such that thehorizontal tangent line to the uppermost surface is spaced apart in moredownward direction than the uppermost horizontal tangent line of theauxiliary joint portion 220 so that the third side 130 may be concave.

Further, each of the upper disc 100 and the lower disc 300 may beconfigured to have one or multiple concave portions 131 on the thirdside 130. The concave portion 131 may reduce unnecessary materialconsumption of the upper disc 100 and the lower disc 300, and make thecentral width narrower so that the upper disc 100 and the lower disc 300have a longer and thinner shape. Although the drawing shows two concaveportions 131 each formed on two sides with respect to the main jointportion 210, this is an example and the number and locations may change.Meanwhile, in addition to the third side 130, the concave portions111,121 may be respectively formed on a first side 110 a and a secondside 120 a as shown in FIG. 9 .

In a second embodiment, referring to FIG. 10 , the upper disc 100 andthe lower disc 300 have a third side 130 a formed in a flat shape, andthe main joint portion 210 and the auxiliary joint portion 220 areformed in a hemispherical shape. In this case, the artificial disc 500is easy to form the shape, and has increased contact area of the upperdisc 100 and the lower disc 300 with the upper vertebra and the lowervertebra, respectively, thereby achieving more stable support.

In a third embodiment, referring to FIG. 11 , the upper disc 100 and thelower disc 300 have the third side 130 a formed in a flat shape, themain joint portion 210 a is formed in a semi-ellipsoidal shape, and theauxiliary joint portion 220 is formed in a hemispherical shape. In thisinstance, preferably, the main joint portion 210 a is horizontallyplaced with the long axis of the ellipse facing the horizontal direction(the left-right direction of the spine) on the plane as shown.

Meanwhile, the foregoing description shows the upper disc 100 and thelower disc 300 configured with an approximate triangular shape as anembodiment. However, the upper disc 100 and the lower disc 300 may havecurved sides, and the sides may be formed in a streamlined shape in theinsertion direction.

A fourth embodiment will be described with reference to FIG. 12 . Theupper disc 100 and the lower disc 300 may be formed with the plane shapein a kidney bean shape including a first curved side 140 and a secondcurved side 150.

In detail, the first curved side 140 is formed along the anterior sideof each of the first auxiliary joint portion 221 a, the main jointportion 210 and the second auxiliary joint portion 222 a and curves onthe plane. The second curved side 150 is connected to the first curvedside 140, and is formed along the posterior side of each of the firstauxiliary joint portion 221 a, the main joint portion 210 a and thesecond auxiliary joint portion 222 a and curves on the plane.

In the drawing, the first curved side 140 curves convexly, and thesecond curved side 150 curves concavely. However, this is an example,and both the first curved side 140 and the second curved side 150 maycurve concavely to form a streamlined shape.

Here, the main joint portion 210 a may be formed in a semi-ellipsoidalshape, and the first auxiliary joint portion 221 a and the secondauxiliary joint portion 222 a may be also formed in a semi-ellipsoidalshape. In this instance, when the main joint portion 210 a is formed ina semi-ellipsoidal shape, the main joint portion 210 a is preferablypositioned with the long axis of the ellipse facing the left-rightdirection on the plane, and the first auxiliary joint portion 221 a andthe second auxiliary joint portion 222 a is preferably positioned withthe long axis of the ellipse facing the front-rear direction on theplane.

In a fifth embodiment, referring to FIG. 13 , compared to FIG. 12 , thefirst auxiliary joint portion 221 and the second auxiliary joint portion222 may be formed in a hemispherical shape. As described above, the mainjoint portion 210 a, the first auxiliary joint portion 221 and thesecond auxiliary joint portion 222 may be formed in various shapesaccording to the surgery condition and the patient's condition.

Meanwhile, the present disclosure may have the same shape of the firstauxiliary joint portion 221 and the second auxiliary joint portion 222as the shape of the corresponding auxiliary joint groove 312 asdescribed above, but as a different embodiment, the shape of the firstauxiliary joint portion 221 and the second auxiliary joint portion 222and the shape of the auxiliary joint groove 312 a in contact with themmay be different from each other. Describing with reference to FIG. 14 ,the first auxiliary joint portion 221 and the second auxiliary jointportion 222 may be formed in a hemispherical shape, and thecorresponding auxiliary joint groove 312 a may be formed in asemi-ellipsoidal shape.

Accordingly, the first auxiliary joint portion 221 and the secondauxiliary joint portion 222 of a hemispherical shape may have theincreased rotational movement in the auxiliary joint groove 312 a of asemi-ellipsoidal shape, and through this, rotation between the upperdisc 100 and the lower disc 300 increases, thereby allowing rotation inall the front-rear direction (x-axis rotation), left-right direction(y-axis rotation) and up-down direction (Z-axis rotation), and allowingfor more diverse and flexible movements of the spine.

While the present disclosure has been hereinabove described withreference to the embodiments shown in the drawings, this is provided forillustration purposes only and it will be appreciated by those skilledin the art that various modifications and equivalents may be madethereto. Therefore, the true technical protection scope of the presentdisclosure should be defined by the technical spirit of the appendedclaims.

[Detailed Description of Main Elements]   100: Upper disc 110, 110a,310:       First side 111, 121, 131, 331:        Concave portion 120,120a, 320:       Second side 130, 130a, 330:       Third side 140: Firstcurved side 150: Second curved side 200: Protruding joint portion 210:Main joint portion 220: Auxiliary joint portion 221: First auxiliaryjoint portion 222: Second auxiliary joint portion 300: Lower disc 311:Main joint groove 312: Auxiliary joint groove 500: Artificial disc

1. An artificial spinal disc inserted between an upper vertebra and alower vertebra, the artificial spinal disc comprising: an upper discformed in a plate shape, with top coupled to the upper vertebra; aprotruding joint portion including a main joint portion protruding froma lower surface of the upper disc, and one or multiple auxiliary jointportions spaced apart from a side of the main joint portion andprotruding from the lower surface of the upper disc; and a lower discformed in a plate shape, with bottom coupled to the lower vertebra, thelower disc having, on an upper surface, a main joint groove in which themain joint portion is seated and an auxiliary joint groove in which theauxiliary joint portion is seated to allow the protruding joint portionto make multidirectional movements.
 2. The artificial spinal discaccording to claim 1, wherein the auxiliary joint portion includes: afirst auxiliary joint portion disposed at a distance on one horizontalside of the main joint portion, and a second auxiliary joint portiondisposed at a distance on the other horizontal side of the main jointportion.
 3. The artificial spinal disc according to claim 2, wherein thefirst auxiliary joint portion and the second auxiliary joint portion aresymmetrically disposed with respect to the main joint portion on aplane.
 4. The artificial spinal disc according to claim 2, wherein eachof the first auxiliary joint portion and the second auxiliary jointportion is formed in a hemispherical shape.
 5. The artificial spinaldisc according to claim 2, wherein each of the first auxiliary jointportion and the second auxiliary joint portion is formed in asemi-ellipsoidal shape.
 6. The artificial spinal disc according to claim5, wherein each of the first auxiliary joint portion and the secondauxiliary joint portion is formed such that a long axis connecting twopoints on a plane is disposed along a front-rear direction of a spine.7. The artificial spinal disc according to claim 2, wherein the mainjoint portion is formed in a hemispherical shape.
 8. The artificialspinal disc according to claim 2, wherein the main joint portion isformed in a semi-ellipsoidal shape.
 9. The artificial spinal discaccording to claim 8, wherein the main joint portion is formed such thata long axis connecting two points on a plane is disposed along aleft-right direction of a spine.
 10. The artificial spinal discaccording to claim 2, wherein the main joint portion protrudes higherthan a protrusion height of the auxiliary joint portion.
 11. Theartificial spinal disc according to claim 1, wherein the protrudingjoint portion is integrally formed with the upper disc.
 12. Theartificial spinal disc according to claim 1, wherein the upper disc andthe lower disc are spaced apart from each other at a distance betweenthe lower surface of the upper disc and the upper surface of the lowerdisc in a range of 3 mm to 6 mm when the protruding joint portion isseated.
 13. The artificial spinal disc according to claim 2, wherein thefirst auxiliary joint portion and the second auxiliary joint portion areformed with a smaller planar area than a planar area of the main jointportion.
 14. The artificial spinal disc according to claim 13, whereinthe auxiliary joint portion is formed such that a center of each of thefirst auxiliary joint portion and the second auxiliary joint portion isdisposed at an anterior portion of a spine with respect to a center ofthe main joint portion.
 15. The artificial spinal disc according toclaim 13, wherein the first auxiliary joint portion and the secondauxiliary joint portion are configured to have a same shape and planararea.
 16. The artificial spinal disc according to claim 2, wherein theupper disc and the lower disc include a first side formed along oneanterior side of the main joint portion and one anterior side of thefirst auxiliary joint portion, a second side having one side connectedto one side of the first side and formed along the other anterior sideof the main joint portion and one anterior side of the second auxiliaryjoint portion to form a set angle with the first side, and a third sidehaving one side connected to the other side of the first side and theother side connected to the other side of the second side and formedalong one posterior side of the first auxiliary joint portion and oneposterior side of the second auxiliary joint portion.
 17. The artificialspinal disc according to claim 16, wherein the upper disc and the lowerdisc have a plane shape of an approximate triangular shape formed by thefirst side, the second side and the third side.
 18. The artificialspinal disc according to claim 17, wherein each of the upper disc andthe lower disc is arranged with the third side facing an anterior sideof a spine.
 19. The artificial spinal disc according to claim 17,wherein each of the upper disc and the lower disc is configured to haveone or multiple concave portions on the third side.
 20. The artificialspinal disc according to claim 2, wherein the upper disc and the lowerdisc include: a first curved side formed along an anterior side of eachof the first auxiliary joint portion, the main joint portion and thesecond auxiliary joint portion, and curved on a plane, and a secondcurved side connected to the first curved side, formed along a posteriorside of each of the first auxiliary joint portion, the main jointportion and the second auxiliary joint portion and curved on the plane.21. An artificial disc insertion method, comprising: inserting anartificial disc into an implantation space between an upper vertebra anda lower vertebra of a human body, the artificial disc including an upperdisc formed in a plate shape, with top coupled to the upper vertebra, aprotruding joint portion including a main joint portion protruding froma lower surface of the upper disc, and one or multiple auxiliary jointportions spaced apart from a side of the main joint portion andprotruding the lower surface of the upper disc, and a lower disc formedin a plate shape, with bottom coupled to the lower vertebra, the lowerdisc having, on an upper surface, a main joint groove in which the mainjoint portion is seated and an auxiliary joint groove in which theauxiliary joint portion is seated to allow the protruding joint portionto make multidirectional movements, wherein the artificial disc isinserted through a lateral or anterolateral approach to a spine and theauxiliary joint portion is first inserted into the implantation space;pushing the artificial disc into the implantation space such that themain joint portion is disposed at a center of the upper vertebra and thelower vertebra on a plane; and adjusting a location of the artificialdisc.